fluid machine connected to a drive source via a magnetic coupling

ABSTRACT

The present invention aims to propose a fluid machine in which a magnetic coupling includes an outer rotor  32  to the cylinder-bottom part of which a drive shaft of the drive component is connected, outer rotor side magnets  33  placed on an inner periphery of the outer rotor, an inner rotor  23  fitted to a drive shaft of the fluid machine, inside the outer rotor, inner rotor side magnets  21  placed on an outer periphery of the inner rotor, whereby attraction workings and repulsion workings between the outer rotor side magnets and the inner rotor side magnets transmit torques of the drive component to the fluid machine, and a sealing assembly  20  a partition part of which is placed between the inner rotor  23  and the outer rotor  32  and surrounds a drive shaft of the fluid machine so as to secure gas-tightness, the shaft including the inner rotor  23  and the inner rotor side magnets  21 ; further an air ventilation device for ventilating a space inside the outer rotor by means of inducing and/or discharging ambient air is provided into the outer rotor  32  of the magnetic coupling so as to cool the sealing assembly  20  and the outer rotor side magnets  33.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No.2006-355474 filed on Dec. 28, 2006, the contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a fluid machine connected to a drivesource via a magnetic coupling, especially to the machine of agas/liquid leak-proof structure (a closed type structure) except thatthere are inlet/outlet ports, including pumps and compressors, themachine being provided with non-contact bearings so as to be oil-supplyfree and driven by the drive source via the magnetic coupling that is apower transmission mechanism for dispensing with a mechanical connectionto the drive source, so that toxic gases and/or nuclear industry-relatedgases and liquids can be treated.

Machines such as compressors and vacuum pumps for vacuum containers usedin nuclear plants are required to be highly durable and reliable,specifically radioactivity-proof and/or wear-proof in order to preventmachine-component deterioration and environmental pollution due toradiations in the plant operation. Moreover, in an operation of amachine as a component of the mentioned plant, it is necessary not onlyto prevent a radioactive environmental pollution from being formed byother machines as the plant components or a component connected to themachine but also to form a border area that isolates the machine fromoutside environment so as not to be affected by the outside environment.Thus, in connection with the mentioned points, the machine isolationfrom the outside as well as the machine cooling has to be designed; inaddition, in order to secure high degree vacuum, are required preventivemeasures, for long continuous operation, against potential difficultiescaused by lubrication structure, sealing structure, bearing structure,and the like.

The situation is similar to the above, in case of the fluid machinessuch as compressors and pumps that treat with such a toxic gas that maycause problems if the gas leaks outside. For instance, in a conventionaltechnology as shown in a patent reference 1 (JP: 1999-44297) by theapplicant of the present invention, the machine is made as a machine ofa closed-type except that there are inlet/outlet ports, by using an airbearing of non-contact-type so as to dispense with lubricant-supply, aswell as a magnetic coupling without mechanical connection to the drivesource.

In the patent reference, as an example of the fluid machine, is shown adouble lapped dry scroll vacuum pump, namely, a pump comprising of anorbiting scroll having a circular-plate and spiral scroll laps set-up onboth side-surfaces of the plate in a direction of the axis of the pumpshaft, and stationary scrolls which are engaged in thesame-spiral-shaped scroll laps of the orbiting scroll in a verticaldirection toward the plate.

The fluid machine structure shown in the patent reference is nowexplained with FIGS. 4 and 5. First, FIG. 5 illustrates a workingprinciple of the vacuum pumps with the spiral scroll laps. Thestationary scroll 11 has a spiral wall-shape vane (lap). The stationaryscroll 11 is fitted into the mentioned orbiting scroll, by making thespiral lap shape of the orbiting scroll 13 substantially the same asthat of the orbiting scroll, and placing the spiral lap of the orbitingscroll 13 point-symmetrically to that of the stationary scroll 11 inFIGS. 5( a) to 5(d), so that the orbiting scroll revolves, with aparallel translation movement around the pump axis, by means of a crankmechanism. A crescent shaped closed space 60 (a compression space) isformed between a lap inside surface 11 b of the stationary scroll 11 anda lap outside surface 13 b of the orbiting scroll 13, and the relativemovement of the scrolls 11 and 13 changes the volume of the compressionspace, thus the suction side will be made vacuum.

In FIG. 5( a), when a lap outside surface 13 b of the orbiting scroll 13and a lap inside surface 11 b of the stationary scroll 11 form a sealedspace to finish an inhaling process, an inhaled gas through an inletport 14 is shut into a compression chamber 60 shown as a dotted regionin FIG. 5 a. Further, when a crank angle of a crank mechanism (notshown) proceeds by 90 degrees as shown in FIG. 5( b), the lap outsidesurface 13 b of the orbiting scroll 13 begin to separate from the lapinside surface 11 b of the stationary scroll 11 around a tail partthereof, to form an open gap space 61 in FIG. 5 b, from which a gas issucked. Further, at an intermediate compression space 62, a compressionprocess is continued, and at a central compression space 63 acompression process is finished so as to start a discharge processthrough an outlet port 64.

With a further advanced crank angle by 90 degrees as shown in FIG. 5 c,in response to an orbiting rotation of the orbiting scroll 13 withoutrevolution, the aforementioned dotted region 60 moves toward a furthercentral location, reducing its volume gradually, then a compressed gasof the chamber is discharged through the outlet port 64.

FIG. 4 shows a cross-sectional outline structure of a double-lapped dryscroll vacuum pump, in which an orbiting scroll 13 having a pair ofspiral scroll laps installed-upright on both sides of a circular plateof the orbiting scroll in a pump axis direction is engaged in stationaryscrolls 11 and 12. As shown in FIG. 4, the vacuum pump comprises a pumpbody 10 and a drive component 30, the pump body 10 comprising a scrollcompressor body 10 a, and sealing assemblies 20 and 25. The sealingassemblies 20, 25 are gas-tightly attached respectively to thestationary scrolls 11, 12 that supports both end-part of a drive shaft16. The pump body 10 further comprises compressed gas inlets 17 and 18through which gases of a pressure higher than the compressor outletpressure are led to the sealing assemblies 20 and 25 respectively, and amagnetic coupling 50 that transmits rotary torque from a drive component30 to the drive shaft 16 without mechanical contact. Thus, the vacuumpump is isolated from the drive component 30 through the magneticcoupling 50 that is a drive torque transmission means, and there is noleak, toward an ambient side, of a pollutant inhaled from the suctionside.

The magnetic coupling 50 is constructed to have an outer rotor (acoupling element) 51 that is of cylindrical shape and has a bottom partconnected to the drive shaft 30 a, drive magnets 52 installed inside theouter rotor 51, and rotary wings 53 for inhaling ambient air throughvents 34 provided in circumference of the outer rotor as well as forcooling the outer rotor 51 and the drive magnets 52. The vacuum pumpside of the magnetic coupling 50 includes an inner rotor 58 attached tothe drive shaft 16 in the pump body, driven magnets 21 installed aroundthe inner rotor, and the sealing assembly 20 that surrounds the innerrotor 58 so as to secure a sealed-up space 22.

A partition part of the sealing assembly 20 is of cylindrical shape withbottom, and placed inside the outer rotor 51 in close proximity to thedrive magnets 52. The driven magnets 21 attached around the inner rotor58 move in close vicinity of the partition part of the sealing assembly20. The driven magnets 21 are arranged so as to effectively repel andattract the drive magnets 52. Thus, in response to the revolution of theouter rotor 51, the inner rotor 58 revolves.

The stationary scroll 11 of the scroll compressor body 10 a comprises acircular plate located vertically to the pump axis and a stationaryscroll lap 11 a of spiral wall shape, the lap 11 a being set-up on afirst side surface of the circular plate, in the pump axis direction.The circular, lid-shaped plate serves as a part of a housing for thescroll compressor body 10 a and the first side surface of the plateserves as a sliding surface for the orbiting scroll lap. On the otherhand, the stationary scroll 12 comprises a circular plate locatedvertically to the pump axis, and a stationary scroll lap 12 a of spiralwall shape, the lap 12 a being set-up on a first side surface of thecircular plate, in the pump axis direction. The circular, lid-shapedplate serves as a part of a housing for the scroll compressor body 10 aand the first side surface of the plate serves as a sliding surface forthe orbiting scroll lap. Further, an orbiting scroll 13 comprises acircular plate located vertically to the pump axis, being mounted on thedrive shaft 16 that are supported by both side bearings thereof so thatthe plate is rotated around an axis of the shaft by a crank mechanism,side surfaces of the plate that serves as sliding surfaces for thestationary scroll laps, and orbiting scroll laps 13 a of spiral wallshape, the laps 13 a being set-up on side surfaces of the circularplate.

In the orbiting scroll 13, the orbiting scroll laps 13 a of the spiralwall shape set-up, in the pump axis direction, on both side surfaces ofa circular disk plate part of the orbiting scroll 13 are engaged intothe stationary scroll laps 11 a and 12 a of spiral wall shape. Further,tip parts of the spiral stationary scroll laps come in contact with bothsliding surfaces of the circular disk plate part of the orbiting scroll13, the tip parts of the stationary scroll being sliding on both theside surfaces of the circular disk plate part. On the other hand, in thestationary scrolls 11 and 12, tip parts of the orbiting scroll laps 13 aof the spiral wall shape come in contact with both the first surfaces ofthe stationary scrolls 11 and 12. The circular disk plate part of theorbiting scroll 13 is mounted on the drive shaft 16 with anoff-centering distance between the shaft axis and the circular diskplate axis. With the aid of a rotation prevention device 57, theorbiting scroll 13 revolves round the drive shaft axis without therotation on the orbiting scroll axis. As mentioned already, thestationary scrolls 11 and/or 12 and the orbiting scroll 13 form aplurality of crescent-moon-shaped compression-spaces, where gas inhaleprocess through an inlet port 14, compression process, and dischargeprocess are performed simultaneously and continuously, thus gas flowthrough an outlet passage 15 a to an outlet 15 is smoothly performed, soas to function as a vacuum pump.

As pointed-out already, both the stationary scrolls 11 and 12 include acircular plate part or a circular disk plate part that serves as a partof a housing for the scroll compressor body 10 a; both the scrolls 11and 12 are gas-tightly built-up through a sealing element 55, andincorporate the orbiting scroll 13; on the other hand, through a sealingelement 56, the stationary scroll 11 and a sealing assembly 20 aregas-tightly built-up; thus, the stationary scrolls 11 and 12 form aclosed space therein, and serve as a casing of a gas-tight structure.

In addition, a compressed inert gas, namely compressed N₂ (nitrogen)here, is blown, through the compressed gas inlets 17 and 18, into theclosed space formed by the orbiting scroll 13, and the stationaryscrolls 11 and 12; thereby, the pressure of the inert gas is higher thanthat of the final discharge gas discharged through the outlet 15,namely, the compressor outlet pressure which is obtained by means of thecompression of closed spaces formed by the orbiting scroll 13, and thestationary scrolls 11 and 12; thus, the gas compressed in the closedspaces does not flow back through the compressed gas inlets 17 and 18.

Another point is that the drive shaft 16 in the pump body is supportedby an oil-less bearing (not shown) made of self-lubricating metals towhich the gas led through the compressed gas inlets 17 and 18 serves asa lubrication medium, In this way, there can be expected no oil-leakagethanks to oil-less lubrication, no diffusion of lubricant mist into thedischarge gas outside, durability improvement of bearings, wastereduction on machine-maintenance; consequently, it becomes possible tooperate the pump for a long period without a rest.

The stationary scroll 12 is provided with cooling fins 59 on a framepart including the circular, lid-shaped plate of the stationary scroll12 so as to enable natural cooling by an ambient air. Further, in thestationary scrolls 11 and 12 including a circular plate part or acircular disk plate part that serves as a part of a housing for thescroll compressor body 10 a, are arranged circular cooling-water jackets54 a, 54 b, 54 c, and 54 d, and cooling-water flows by a cooling-watercirculating means (not shown) comprising of radiators (not shown), andcooling-water circulating pumps (not shown). Thus, the forced cooling ofthe stationary scrolls 11 and 12 from the back sides thereof isaccomplished.

As mentioned above, the compressed inert gas, the pressure of which ishigher than that of the final discharge gas discharged through theoutlet port 15, is led through the compressed gas inlets 17 and 18,toward each end side of drive shaft bearings, and the inert gas isdischarged through the outlet port 15. As a result, the gas compressedin the closed spaces does not flow back through the compressed gasinlets 17 and 18. Moreover, the vacuum pump is gas-tightly isolated fromoutside (except that there are connection parts such as the inlet port14, the outlet port 15, the compression gas inlet 17 and 18). Further,the pump needs no sealing elements as to the magnetic coupling 50 thatis a drive torque transmission means without mechanical contact. Thus,even when radioactive pollution materials is inhaled through the inletport from the atomic energy plant side, the pollutant cannot leakthrough the pump toward an ambient side.

Thus, the vacuum pump as a fluid machine as described in the patentreference can be given a gas-tight isolation due tonon-mechanical-contact property of the magnetic coupling 50 that is adrive torque transmission means, the pump leaking outside no pollutantfrom a suction side. Further, since the pump is provided with anoil-less bearing made of self-lubricating metals or a gas bearing, it ispossible to continue the pump operation for a long period without astop. Furthermore, since the pump is provided with the cooling fins 59on the circular, lid-shaped plate-frame part of the stationary scroll12, as well as provided with circular cooling-water jackets 54 a, 54 b,54 c, and 54 d for forced cooling in the frame part, sufficientprevention measures are taken against a possible heat hazard derivedfrom gas compressed in a space between the stationary scrolls 11, 12 andthe orbiting scroll 13.

However, the gas sucked through the inlet port 14 is compressed in thespace between the stationary scrolls and the orbiting scroll engagedtherein, producing remarkable heat. Accordingly, a part of the heat isconducted to the magnetic coupling 50, and in an operation of the pumpfor a period to some extent, a heat also comes to the magnetic coupling50 from the drive component 30. Nevertheless, measures for cooling themagnetic coupling 50 are only rotary wings 53 fitted on an outer surfaceof the outer rotor 51. There is no specific measure for cooling thedrive magnets 52 placed inside the outer rotor 51, and for cooling thesealing assembly 20.

On one hand, it is important, from a viewpoint of the torquetransmission from the drive component to the inner rotor, to keep acertain range of a clearance between the drive magnets 52 and thesealing assembly 20 and of a clearance between the sealing assembly 20and the driven magnets 21 fitted on the outer surface of the inner rotor58. If temperatures of the sealing assembly 20 and/or the drive magnets52 increase, spacing between the sealing assembly 20 and the drivemagnets 52 is changed. It may happen at worst that both components 20and 52 touch each other to damage the magnetic coupling 50. On the otherhand, the spaces between the sealing assembly 20 and the drive magnets52 may expand such that magnetic flux densities reaching the drivenmagnets are weakened, an ordinary torque transmission being spoiled.

From a viewpoint of the rotary wings 53 fitted on an outer surface ofthe outer rotor 51, the wings are apt to be of large size, requiring alarge space for the wings to rotate; bringing a large design of themagnetic coupling 50 and the whole fluid machine all the more.

SUMMARY OF THE INVENTION

In light of the conventional situation as described so far, the presentinvention relates to fluid machines such as compressors and pumps thattreat with such a toxic gas as may cause problems if the gas leaksoutside, and the object of the present invention is to provide agas-tightly sealed type fluid machine connected to a drive component viaa magnetic coupling, in which an efficient cooling for the magneticcoupling is performed without enlarging the space for the magneticcoupling to be built-in.

To solve the problem, the present invention proposes a fluid machineconnected to the drive component via a magnetic coupling, having a drivecomponent, and a fluid machine composed of a pump unit includingcompressors, being connected to the drive component via a magneticcoupling; said magnetic coupling including, an outer rotor to thecylinder-bottom part of which a drive shaft of the drive component isconnected, outer rotor side magnets placed on an inner periphery of theouter rotor, an inner rotor fitted to a drive shaft of the fluidmachine, inside the outer rotor, and inner rotor side magnets placed onan outer periphery of the inner rotor, whereby attraction workings andrepulsion workings between the outer rotor side magnets and the innerrotor side magnets transmit torques of the drive component to the fluidmachine; in which the fluid machine is provided with a pair of sealingassemblies that encloses both end parts of a drive shaft of the fluidmachine so as to bring the fluid machine a gas-tightly sealed conditionexcept that there are a gas inlet port, a gas outlet port, andcompression gas inlets, and further an air ventilation device forventilating a space inside the outer rotor by means of inducing and/ordischarging ambient air is provided in the outer rotor of the magneticcoupling so as to cool the sealing assembly of the magnetic couplingside, and the outer rotor side magnets.

By providing, into the outer rotor of the magnetic coupling, an airventilation device for ventilating a space inside the outer rotor bymeans of inducing and/or discharging ambient air, potential damages ofthe magnetic coupling due to insufficient cooling as mentioned above canbe evaded. Namely, even when the heat generated according to gascompression in the fluid machine or the heat derived from the drivecomponent is conducted to the magnetic coupling, the sealing assembly ofthe magnetic coupling side and the outer rotor side magnets are cooleddown by the induced and/or discharged ambient air. As a result, itbecomes possible to evade possible reduction of the clearances betweenthe outer rotor side magnets and the sealing assembly of the magneticcoupling side to evade possible mechanical contact therebetween. On theother hand, it becomes also possible to evade torque transmissionfailure due to weakened magnetic flux densities reaching the drivenmagnets, in case when the clearances are widened.

Moreover, since the air ventilation device is fitted on the outer rotoritself, neither upsizing of the coupling nor useless large space isrequired. As a result, the device can realize a compact design of thefluid machine.

Since blades are fitted therein with an inclination to a rotationaldirection of the outer rotor so as to form ventilation slits aroundsurface walls of the outer rotor, the air ventilation device can bequite simply realized.

A preferable embodiment of the present invention is to install the airventilation device in a drive component side cylinder-bottom part of theouter rotor, in a cylinder-periphery part of the outer rotor, in acylinder-periphery part of the outer rotor between the outer rotor sidemagnets attached on inner periphery of the outer rotor, in a fluidmachine side cylinder-periphery end-part of the outer rotor, or in aplural locations among said lacations.

Further, as the air ventilation devices (blade/slits) are placed at thefluid machine side and the drive component side across an band area ofthe cylinder-periphery part of the outer rotor where the outer rotorside magnets are located inside the outer rotor, and each air inducingand/or air discharging momentum at each blade/slit can be adjustablydesigned, so that a ventilation air does not stagnate inside the outerrotor. Thus, the sealing assembly of the magnetic coupling side and theouter rotor side magnets can be effectively cooled.

As described so far, with such a simple structure as an air ventilationdevice is installed in an outer rotor of a magnetic coupling, thepresent invention prevents a fluid machine connected to the drivecomponent via a magnetic coupling from being damaged by mechanicalcontacts between a sealing assembly of the magnetic coupling side andouter rotor side magnets, the contacts being derived from reductions ofclearances between the outer rotor side magnets and the sealing assemblyof the magnetic coupling side, and the clearance reduction isattributable to a heat generated according to gas compression in thefluid machine and conducted to the magnetic coupling, or a heat derivedfrom the drive component and conducted to the magnetic coupling.Contrary to the above, there may be a case wherein excessive clearancesare designed in advance so as to avoid the contacts such as describedabove. In such a case, the clearances are too sufficient until themagnetic coupling is uselessly heated-up; as a result, is brought sparsemagnetic flux reaching the driven magnets from the driven magnets aswell as is brought torque transmission failure. The present inventionprevents a fluid machine connected to the drive component via a magneticcoupling also from being attacked by this torque transmission failure.

Moreover, since the air ventilation device is fitted on the outer rotoritself, an introduction of the device requires neither upsizing of themagnetic coupling nor useless large space around the outer rotor. As aresult, the device can realize a compact design of the fluid machine.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail with reference tothe preferred embodiments of the invention and the accompanyingdrawings, wherein:

FIG. 1 shows, in a sectional view, an outline structure of adouble-lapped dry scroll vacuum pump as an example of a fluid machineconnected to a drive component via a magnetic coupling according to thepresent invention;

FIG. 2 shows an enlarged sectional view of a magnetic coupling in FIG.1;

FIGS. 3A, 3B, 3C, 3D, 3E, and 3F are sectional views of a structure ofblades and slits as an air ventilation device installed in an outerrotor of the magnetic coupling according to the invention and locationsas to the device;

FIG. 4 shows an outline structure of a conventional double-lapped dryscroll vacuum pump in a sectional view; and

FIGS. 5 a, 5 b, 5 c, and 5 d illustrate transitions from a state thatsuction process is finished to compression process, as well as fromcompression process to discharge process, in a scroll compression bodyof a scroll vacuum pump.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereafter, the present invention will be described in detail withreference to the embodiments shown in the figures. However, thedimensions, materials, shape, the relative placement and so on of acomponent mentioned in these embodiments shall not be construed aslimiting the scope of the invention thereto, unless especially specificmention is placed.

FIG. 1 shows, in a sectional view, an outline structure of adouble-lapped dry scroll vacuum pump as an example of a fluid machineconnected to a drive component via a magnetic coupling according to thepresent invention. FIG. 2 shows an enlarged sectional view of a magneticcoupling 31 in FIG. 1; FIG. 3 shows, in a sectional view, a structure ofslits (blades) as an air ventilation device installed in an outer rotor32 of the magnetic coupling according to the invention. In order toexplain a fluid machine of the present invention, an emphasis is placedon an example of a double-lapped dry scroll vacuum pump asaforementioned with FIG. 4 according to the patent reference. However,the present invention can be obviously applied to other general fluidmachines such as compressors, pumps and so on, so long as the fluidmachines are connected to a drive source via a magnetic coupling. In thefollowing explanation, the same numerals are basically used forindicating related components/items as shown in FIG. 4. Further, hereand there in the following explanation, there may be some explanationoverlaps with the description up to now as to FIG. 4 for understandingthe present invention easily.

At first, a simple outline of the present invention is given. Accordingto the present invention, in a fluid machine represented with a vacuumpump as already explained with FIG. 4, blades are installed in acoupling element 51 (32 in FIG. 1) so as to introduce ventilation slitsand to ventilate a space inside the coupling element 51. (Hereafter, thecoupling element 51 (32) will be referred to as an outer rotor 51(32).)As illustrated in FIGS. 2 and 3, the blades are fitted with aninclination to a rotational direction of the outer rotor, to induce anambient air into the space and discharge the induced air outside thespace in response to a rotation movement of the outer rotor, resultingin that a sealing assembly 20 of the vacuum pump and drive magnets(outer rotor side magnets) 52 (33 in FIG. 1) of a magnetic coupling arecooled.

In the air ventilation device, the blades are fitted into the outerrotor 51 (32 in FIG. 1) with an inclination to a rotational direction ofthe outer rotor 51 (32 in FIG. 1) so that the blades induce an ambientair into the space inside the outer rotor 51 (32 in FIG. 1) as well asdischarge the induced air outside the outer rotor 51 (32 in FIG. 1); theblades and/or slits as the air ventilation device are installed in adrive component (30) side cylinder-bottom part of the outer rotor 51, ina cylinder-periphery part of the outer rotor 51, between outer rotorside magnets 52 (33 in FIG. 1) attached on inner periphery of the outerrotor 51, in a vacuum pump side cylinder-periphery end-part of the outerrotor 51, or in a plurality of the above locations.

The blade/slits (air ventilation device) are preferably placed at bothsides of the vacuum pump side (the fluid machine side) and the drivecomponent 30 side across an band area of the cylinder-periphery part ofthe outer rotor where the outer rotor side magnets 52 (33 in FIG. 1) arelocated inside the outer rotor, and each air inducing and/or airdischarging momentum at each blade/slit can be adjustably designed, sothat a ventilation air does not stagnate inside the outer rotor. Thus,the sealing assembly 20 of the magnetic coupling side and the outerrotor side magnets 52 (33 in FIG. 1) can be effectively cooled.

Thus far, is described the outline of a fluid machine connected to adrive component via a magnetic coupling according to the invention.Hereafter, with reference to FIGS. 1 and 2, is explained a double-lappeddry scroll vacuum pump as an example of a fluid machine connected to adrive component via a magnetic coupling according to the invention. Likethe vacuum pump explained with FIGS. 4 and 5, the vacuum pump shown inFIG. 1 comprises an orbiting scroll 13, having a circular plate andspiral scroll laps set-up on both side-surfaces of the plate protrudingin a direction of an axis of pump shaft, and stationary scrolls 11 and12, such that the scroll laps are engaged in the same-spiral-shapedscroll laps of the stationary scrolls.

In FIG. 1, a vacuum pump is composed of a pump body 10, a drivecomponent 30, and a support member 35 for supporting the pump body 10and the drive component 30. The pump body 10 includes a scrollcompressor body 10 a, a pair of sealing assemblies (enclosures) 20 and25 that are gas-tightly attached respectively to stationary scrolls 11and 12 that support each end-part of a drive shaft 16 rotating anorbiting scroll so that a protrude of each end-part is enclosed by thesealing assembly 20, 25 respectively. The pump body 10 further includescompressed gas inlets 17 and 18 through which gases with pressure higherthan the compressor outlet pressure (lap compression gas pressure) areled into the sealing assemblies 20 and 25 respectively, and a magneticcoupling 31 that transmits rotary torque from the drive component 30 tothe drive shaft 16 without mechanical contact.

Thus, the vacuum pump is isolated from the drive component 30 by meansof the magnetic coupling 31 that is a drive torque transmission means,and there is no leak of a pollutant inhaled from the suction side,toward an ambient side.

The magnetic coupling 31 of the drive component 30 side is composed of acylindrical-shaped outer rotor 32 having a bottom part connected to thedrive shaft 30 a, and drive magnets (outer rotor side magnets) 33installed inside the outer rotor 32. The magnetic coupling 31 of thevacuum pump side is provided with a inner rotor 23 connected to a driveshaft 16 in the pump body, driven magnets (inner rotor side magnets) 21installed around the inner rotor, and a sealing assembly 20 thatsurrounds the inner rotor 23 so as to secure a sealed-up space 22.(Hereafter, the pump-side coupling element 23 will be referred to as aninner rotor 23.)

A partition of the sealing assembly 20 is of cylindrical shape, andplaced inside the cylindrical-shaped outer rotor 32 in close proximityto the drive magnets 33. The inner rotor 23 is composed such that thedriven magnets 21 attached around the inner rotor 23 move, in closevicinity of the partition of the sealing assembly 20, so as toeffectively repel and attract the drive magnets (outer rotor sidemagnets) 33 arranged inside the outer rotor 32. Thus, the inner 23 isrotated in response to the rotation of the outer rotor 32.

The stationary scroll 11 of the scroll compressor body 10 a is composedof a circular plate located vertically to the pump axis, and astationary scroll lap 11 a of spiral wall shape set-up on a first sidesurface of the circular plate in the pump axis direction. The circular,lid-shaped plate serves as apart of a housing for the scroll compressorbody 10 a and a first side surface of the plate serves as a slidingsurface for the orbiting scroll lap.

On the other hand, the stationary scroll 12 is composed of a circularplate located vertically to the pump axis, and a stationary scroll lap12 a of spiral wall shape set-up on a first side surface of the circularplate in the pump axis direction. The circular, lid-shaped plate servesas a part of a housing for the scroll compressor body 10 a and a firstside surface of the plate serves as a sliding surface for the orbitingscroll lap.

The orbiting scroll has a circular plate to the pump axis, which isvertically installed to the pump axis on the drive shaft 16 supported byboth side bearings, to be rotated around the shaft, and orbiting scrolllaps 13 a of spiral wall shape set-up on side surfaces of the circularplate.

In the orbiting scroll 13, the orbiting scroll laps 13 a of the spiralwall shape set-up on both side surfaces thereof in the axial directionare engaged into the stationary scroll laps 11 a and 12 a of spiral wallshape. Further, tip parts of the spiral stationary scroll laps come incontact with both side surfaces of the circular disk plate part of theorbiting scroll 13, to slide on both the side surfaces of the circulardisk plate part. On the other hand, in the stationary scrolls 11 and 12,tip parts of the orbiting scroll laps 13 a of the spiral wall shape comein contact with both the first side surfaces of the stationary scroll 11and 12. The circular disk plate part of the orbiting scroll 13 ismounted on the drive shaft 16 with an off-centering distance between theshaft axis and the circular disk plate axis. With the aid of a rotationprevention device (not indicated in FIG. 1), the orbiting scroll 13revolves round the drive shaft axis without the rotation on the orbitingscroll axis. As mentioned already, the stationary scrolls 11 and/or 12and the orbiting scroll 13 form a plurality of crescent-moon-shapedcompression spaces (compression-rooms), where inhale process through aninlet port 14, compression process, and discharge process are performedsimultaneously and continuously, so that gas flows through an outletpassage 15 a to an outlet 15 smoothly, functioning as a vacuum pump.

In addition, a compressed inert gas, namely compressed N₂ (nitrogen)here, is blown, through the compressed gas inlets 17 and 18, into theclosed space formed by the orbiting scroll 13 and the stationary scrolls11 and 12 to be compressed in the space. Since the pressure of the inertgas is higher than that of the final discharge gas discharged throughthe outlet 15, namely, the compressor outlet pressure after compressedin the closed spaces, the gas compressed in the closed spaces does notflow back through the compressed gas inlets 17 and 18.

Another point is that the drive shaft 16 in the pump body is supportedby an oil-less bearing (not shown) made of self-lubricating metals or agas bearing (not shown) where the gas led through the compressed gasinlets 17 and 18 serves as a lubrication medium. Since there can beexpected no oil-leakage thanks to oil-less lubrication, no diffusion oflubricant mist into the discharge gas outside, durability improvement ofbearings, waste reduction on machine-maintenance, as described above, itbecomes possible to operate the pump for a long period without a rest.Further, the drive shaft is provided with balance-weights 42 and 43 soas to mitigate an imbalance (so-called crank unbalance) of the crankmechanism.

The stationary scroll 12 is provided with cooling fins (not shown inFIG. 1) on a frame part including the circular, lid-shaped plate of thestationary scroll 12 so as to enable natural cooling by an ambient air.In the stationary scrolls 11 and 12 including a circular plate part or acircular disk plate part that serves as a part of a housing for thescroll compressor body 10 a, circular cooling-water jackets (not shownin FIG. 1) are arranged, and cooling-water flows by a cooling-watercirculating means (not shown) comprising of radiators (not shown), andcooling-water circulating pumps (not shown). Thus, the forced cooling ofthe stationary scrolls 11 and 12 from the back sides thereof isaccomplished.

As mentioned above, the compressed inert gas, the pressure of which ishigher than that of the final discharge gas discharged through theoutlet port 15, is led through the compressed gas inlets 17 and 18,toward each end side of drive shaft bearings, to be discharged throughthe outlet port 15. As a result, the gas compressed in the closed spacesdoes not flow back through the compressed gas inlets 17 and 18.Moreover, the vacuum pump is gas-tightly isolated from outside (exceptthat there are connection parts such as the inlet port 14, the outletport 15, the compression gas inlet 17 and 18). Further, the pump needsno sealing elements as to the magnetic coupling 31 that is a drivetorque transmission means without mechanical contact. Thus, even whenradioactive pollution material is sucked through the inlet port from theatomic energy plant side, the pollutant cannot leak through the pumptoward an ambient side. In this connection, the patent referencedescribes a further detail about a double-lapped dry scroll vacuum pumpas an example of a fluid machine connected to a drive component via amagnetic coupling.

FIG. 2 shows an enlarged sectional view of magnetic coupling 31 in FIG.1 of the present invention. The magnetic coupling 31 is provided with atleast one air ventilation device that is installed in an outer rotor 32composing a member of the magnetic coupling 31. The air ventilationdevice is arranged, for instance, at a part indicated as referencenumeral 36 in a drive component side cylinder-bottom part of the outerrotor 32, and/or at apart indicated as reference numeral 39 in a vacuumpump side cylinder-periphery end-part of the outer rotor 32, so as toform air streams as illustrated with arrows in FIG. 2. Here, thereference numeral 20 indicates an sealing assembly (an enclosure), 21indicates inner rotor side magnets, 23 is an inner rotor, 30 a is adrive shaft of a drive component 30, 33 indicates outer rotor sidemagnets, and 34 indicates a vent.

Besides the above-mentioned parts 36 and 39 pointed-out beforehand, theair ventilation device may be provided in a cylinder-periphery part ofthe outer rotor 32, in a cylinder-periphery part of the outer rotorbetween outer rotor side magnets 33 (in FIG. 1) attached on innerperiphery of the outer rotor 32, or the like. The blade/slits (airventilation device) are preferably placed at both of the vacuum pumpside (the fluid machine side) and the drive component 30 side across anband area of the cylinder-periphery part of the outer rotor where theouter rotor side magnets 33 (in FIG. 1) are located, and further eachair inducing and/or air discharging momentum at each blade/slit ispreferably adjusted, so that aventilation air does not stagnate insidethe outer rotor. The magnetic coupling is effectively cooled especiallyby airflows in the pump axis direction through a gap space between theouter rotor side magnets and the inner rotor side magnets. Here, a partof the ventilation devices play role of upstream passages while theremaining devices play role of downstream passages, thereby passageresistance of the downstream passages is preferably smaller than that ofthe upstream passages or inducing momentum of the upstream passages ispreferably larger than that of the down stream passages.

FIGS. 3A, 3B, 3C, 3D, 3E, and 3F illustrate the structure andinstallation locations as to the air ventilation device. FIG. 3F shows,in a sectional view, the locations where the air ventilation devices areinstalled in the outer rotor 32. Reference numerals 30 a and 33 indicatea drive shaft of a drive component 30, and drive magnets (outer rotorside magnets) 33 respectively. The numerals 36 indicates an airventilation device installed in a drive component side cylinder-bottompart of the outer rotor 32, as shown in FIG. 3A which is across-sectional view of line A-A′, the numerals 37 indicates an airventilation device installed in a cylinder-periphery part of the outerrotor 32, as shown in FIG. 3B which is a cross-sectional view of lineB-B′, the numerals 38 indicates an air ventilation device installed in acylinder-periphery part of the outer rotor between outer rotor sidemagnets 33 attached on inner periphery of the outer rotor 32, as shownin FIG. 3C which is a cross-sectional view of line C-C′, and thenumerals 39 indicates an air ventilation device installed in a vacuumpump side cylinder-periphery end-part of the outer rotor 32, as shown inFIG. 3D which is a cross-sectional view of B-B′.

As illustrated in FIG. 3E, an air ventilation device installed in eachlocation is composed, for example, to be a plurality of blades fittedinto the outer rotor 32 with an inclination to a rotational direction ofthe outer rotor 32, as illustrated in FIG. 3E. Through the slits formedbetween the blades 40, an ambient air is induced into the space insidethe outer rotor 32 as well as the induced air is discharged outside theouter rotor 32.

As indicated in FIG. 3A, the air ventilation device 36 installed in thecylinder-bottom part of the outer rotor 30 at the drive component 30side may be a circular shape centering around the drive shaft 30 a ofthe drive component 30. As a matter of course, there may be solid hub(rib) parts in an annular space of blades and slits from a viewpoint ofpractical strength design. In FIG. 3B, the air ventilation device 37 islocated in a cylinder-periphery part of the outer rotor 32. The locationarea may be any part of the cylinder-periphery part of the outer rotor32 except the places where the drive magnets occupy, for instance, aband area of the cylinder-periphery part of the outer rotor where theouter rotor side magnets 33 are located inside the outer rotor 32.

In the air ventilation device 38 shown in FIG. 3C, blades are placed ina cylinder-periphery part of the outer rotor, between outer rotor sidemagnets 33, across an band area of the cylinder-periphery part of theouter rotor where the outer rotor side magnets 33 are located inside theouter rotor 32. In FIG. 3C, the areas in which the drive magnets 33 arearranged protrude inside toward the coupling axis than the areas of theblades/slits 38. However, the protrusion is not a prerequisite, ofcourse, the inner diameters of both areas, namely, the magnet areas andthe blade/slit areas may be the same.

The air ventilation device 39 shown in FIG. 3D is installed in a vacuumpump side cylinder-periphery end-part of the outer rotor 32. With theslits directed so as to induce an ambient air inside, the sealingassembly 20 can be effectively cooled as an airflow blows immediatelytoward the partition part of the sealing assembly 20.

Further, as mentioned before, with the air ventilation devices 36, 37,38, and 39 that are placed at both of the vacuum pump side (the fluidmachine side) and the drive component 30 side across an band area of thecylinder-periphery part of the outer rotor where the outer rotor sidemagnets 33 are located. With larger differences as to airinducing/discharging amounts between upstream sides and downstreamsides, the sealing assembly 20 can be effectively cooled without airflowstagnation (as a whole) inside the outer rotor 32.

For obtaining the above effect, for instance, the slit area of theupstream sides may be reduced than that of the downstream sides, anambient air may be induced inside the outer rotor 32 through theventilation device 36 and the induced air is discharged outside theouter rotor 32 through the ventilation devices 38 and 39, an ambient airmay be induced through the ventilation device 36 and the induced air isdischarged through the ventilation devices 36 and 37, or the numbers ofthe ventilation devices on discharge side may be reduced than that oninduction side.

As described so far, in a fluid machine connected to the drive componentvia a magnetic coupling according to the present invention, the airventilation devices 36, 37, 38, and 39 for inducing an ambient air areinstalled in an outer rotor 32 of a magnetic coupling 31 so as to coolthe sealing assembly (an enclosing partition) 20 and the outer rotorside magnets (drive magnets) 33. By the structure, the enclosingpartition 20 and the drive magnets 33 are cooled by the induced ambientair, in a case where a gas/fluid compression process in the fluidmachine generates a heat or when a heat derived from the drive component30 is conducted to the magnetic coupling. As a result, it becomespossible to evade possible reduction of the clearances between the outerrotor side magnets 33 and the sealing assembly 20, that is, it becomespossible to evade possible mechanical contact therebetween. Further,torque transmission failure due to weakened magnetic flux densitiesreaching the driven magnets (inner rotor side magnets) 22 can be evaded,in a case when the clearances between the outer rotor side magnets 33and the sealing assembly 20 are widened.

Moreover, since the air ventilation device is fitted on the outer rotoritself 32, upsizing of the magnetic coupling 31 or useless large spaceattended by the conventional rotary wings around the outer rotor is notrequired. As a result, the device can realize a compact design andproduction as to both the magnetic coupling and the fluid machine.

The present invention can realize a fluid machine connected to a drivesource via a magnetic coupling, having high durability and reliability,since the magnetic coupling is effectively cooled, granting that heatsare conducted to the magnetic coupling from the fluid machine or fromthe drive source.

1. A fluid machine connected to the drive component via a magneticcoupling, comprising of, a drive component, and a fluid machine composedof a pump unit including compressors, being connected to the drivecomponent via a magnetic coupling; said magnetic coupling comprising, anouter rotor to the cylinder-bottom part of which a drive shaft of thedrive component is connected, outer rotor side magnets placed on aninner periphery of the outer rotor, an inner rotor fitted to a driveshaft of the fluid machine, inside the outer rotor, and inner rotor sidemagnets placed on an outer periphery of the inner rotor, wherebyattraction workings and repulsion workings between the outer rotor sidemagnets and the inner rotor side magnets transmit torques of the drivecomponent to the fluid machine; the fluid machine being provided with apair of sealing assemblies that encloses both end parts of a drive shaftof the fluid machine so as to bring the fluid machine a gas-tightlysealed condition except that there are a gas inlet port, a gas outletport, and compression gas inlets; wherein an air ventilation device forventilating a space inside the outer rotor by means of inducing and/ordischarging ambient air is provided in the outer rotor of the magneticcoupling so as to cool the sealing assembly of the magnetic couplingside, and the outer rotor side magnets.
 2. A fluid machine connected tothe drive component via a magnetic coupling of claim 1, wherein the airventilation device composed of blades and/or slits, the blades beingfitted into a periphery part of the outer rotor with an inclination to arotational direction of the outer rotor and the slits for ventilationbeing formed space from a blade to a blade.
 3. A fluid machine connectedto the drive component via a magnetic coupling of claim 1, wherein theair ventilation devices are installed in a drive component sidecylinder-bottom part of the outer rotor, in a cylinder-periphery part ofthe outer rotor, in a cylinder-periphery part of the outer rotor betweenthe outer rotor side magnets attached on inner periphery of the outerrotor, in a fluid machine side cylinder-periphery end-part of the outerrotor, or in the plural locations among said locations.
 4. A fluidmachine connected to the drive component via a magnetic coupling ofclaim 1, wherein the air ventilation devices are provided at both of thefluid machine side and the drive component side across an band area ofthe cylinder-periphery part of the outer rotor where the outer rotorside magnets are located, a part of the ventilation devices playing roleof upstream passages and the remaining devices playing role ofdownstream passages, whereby passage resistance of the downstreampassages is smaller than that of the upstream passages or wherebyinducing momentum of the upstream passages is larger than that of thedown stream passages.